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I install and configure l7-filter:

sudo apt-get install l7-filter-userspace l7-protocols
sudo cp /usr/share/doc/l7-filter-userspace/examples/sample-l7-filter.conf /etc/l7-filter.conf
sudo l7-filter -f /etc/l7-filter.conf -q 2 -v
sudo iptables -t mangle -A PREROUTING -j NFQUEUE --queue-num 2
sudo iptables -t mangle -A OUTPUT -j NFQUEUE --queue-num 2 

l7-filter loads all protocol and doesn't give error:

Got packet, had no ct:  udp      17 src= dst=
sport=45659 dport=53
Got packet, had no ct:  udp      17 src= dst=
sport=34234 dport=53
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What happened? What did you expect to happen? Does the "sample-l7-filter.conf" actually do anything? If there were no errors how do you know it didn't work? – DerfK Feb 16 '11 at 18:01
l7-filter does not set markers – bindbn Feb 16 '11 at 18:06
up vote 1 down vote accepted

Try load ip_conntrack_netlink and nf_conntrack_ipv4 modules:

sudo modprobe ip_conntrack_netlink
sudo modprobe nf_conntrack_ipv4
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How did you find them? – bindbn Feb 16 '11 at 18:08
@bindbn In Ubuntu 10.10, when run l7-filter I get the WARNING – ooshro Feb 16 '11 at 18:12

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